Conventional face milling cutters with round or polygonal parallel cutting and seating faces extending in nearly axial planes normally require roughing and finishing cuts and frequently further surface smoothing operations, particularly in cutting tough metal such as titanium or alloy steels having difficult machining properties. Normally when such cutters are employed in making relatively shallow face milling cuts only a very limited minor portion of the cutting edge is involved in the cutting action; and any wiping cutting edge to effect a smooth surface finish is provided in one or more auxiliary inserts specially located in the cutter body for such purpose. Examples of such prior art are found in U.S. Pat. Nos. 3,303,555, 3,371,397 and 3,391,438.
It is known in some prior art constructions to place one or more inserts with main parallel faces extending generally circumferentially. In such cases the faces may extend in substantially diagonal conical corner portions of the cutter body as in the case of U.S. Pat. Nos. 1,460,838 (FIG. 3), 3,716,900 and 3,818,562 as well as German Pat. No. 2,016,193. In some face milling cutters employing flat circular inserts the main cutting face for one or more finishing inserts has been located nearly parallel to a radial plane normal to the axis, examples being shown in U.S. Pat. Nos. 3,371,397, 3,464,098. In one prior art U.S. cutter Pat. No. 3,708,843, FIG. 1 of which superficially is closest in general appearance to applicant's construction of any known prior art, a plurality of flat generally square tungsten carbide inserts, having two opposite sides provided with rounded edges extending the length of the sides, are located in corner pockets the seating surfaces of which all lie in a shallow cone having a small angular relationship with a radial plane extending normal to the axis. However, the cutter is such case is a boring tool in no way adapted to provide face milling cutting.